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6
votes
3answers
354 views

Intersecting bug trail [closed]

A man picks up a huge circular dart board and shoots paintballs at it. $n$ paintballs manage to hit it. They are random and point-sized, for the purpose of this question. A bug is somewhere on the ...
11
votes
2answers
699 views

Ninety-nine non-negative numbers

Alice and Bob play the following game with $99$ numbers $M_1,\ldots,M_{99}$. In the beginning, the $99$ numbers take the values $1,2,4,8,16,\ldots,2^{97},2^{98}$. Then Alice and Bob alternatingly ...
1
vote
3answers
1k views

Where are the missing guests?

I'm Caucasian and my fiancé is Chinese - I met her on a trip to Tahiti though as chance would have it, it turned out that we actually grew up in adjacent towns in Ohio. We decided to have a very ...
8
votes
1answer
494 views

Can anyone help me remember the title to this song?

This is related to my previous question, Q: Nice song, pity about the words I have a terrible memory for the words of songs and I'm even worse when it comes to their titles. I'd really like to find ...
10
votes
2answers
6k views

Can you solve this devilish Junior Jumble?

In the game Undertale, there is a character named Papyrus who believes that the Jumble puzzle is much harder than the daily crossword. Help prove him right by trying to solve this brainteaser:
6
votes
1answer
682 views

Are there any sets of 9 numbers that can form two essentially distinct magic squares?

It's known that the numbers 1 to 9 can only form eight different magic squares, which are all rotations and reflections of each other. Is there any set of 9 distinct numbers that can form two ...
9
votes
2answers
448 views

Save the world from Dr. Mysterious

My name is ????? You must find out Dr. Mysterious's name, which is your greatest weapon against him (it gives you power over him). His slave, Mr. Useless, has sent you some information but it is ...
9
votes
1answer
277 views

Strange implications with $aN$, $eF$ and $gH$

Given the implications $$aN\implies S$$ $$eF\implies I$$ $$gH\implies M$$ could you please complete the following implication: $$nS\implies ?$$ (The answer is one of the letters $T$, $A$, $L$,...
4
votes
1answer
242 views

Flipping coin quadruples

Eighteen coins are arranged in a circle. In the beginning, all eighteen coins show tails. The following two moves are allowed: Simultaneously flipping over four consecutive coins (so that tails ...
4
votes
1answer
407 views

The Witches Have Overdone It

Alice the Witch had a great night last night. She'd had a Halloween night house party with five of her closest friends from Witch College that she hadn't seen for ages. They had been drinking and ...
3
votes
2answers
260 views

Mixed Backwards Hangmen

My previous backward hangman (created originally by Alex, see here), was still solved too quickly, so I thought I'd make another tweak to make it a bit more tricky. This time, whatever the bizarre ...
5
votes
5answers
434 views

The smallest value on the blackboard

The square numbers $ 1^2, 2^2, 3^2, 4^2, \cdots, 100^2, 101^2 $ are written on the blackboard. Each minute any two numbers are wiped out, and the absolute value of their difference is written instead....
11
votes
1answer
457 views

The mathematical meta magician

The famulus of a mathematical meta magician puts infinitely many cards into a top hat. Each of these cards carries a non-negative integer. The top hat contains exactly $n$ cards showing the integer $...
-6
votes
1answer
197 views

What will be the missing number? [closed]

What number comes next? 11,13,17,19,23,25,?
6
votes
1answer
597 views

Yet another backwards hangman

Insprired by the previous backwards hangman (created originally by Alex, see here), which was solved so quickly, I though I'd make another one. Hopefully slightly harder! Three solutions in a minute ...
15
votes
3answers
850 views

There's a Ghost of a Chance!

It's the eve of Halloween, and everyone is gathering for the Monster Bash at the Monster Mansion. The same haunts are hosting this year's event: Count Dracula, Frankenstein's Monster, Wolfman, Mummy, ...
11
votes
3answers
980 views

Don't get caught by the Hang Man

Bringing back the Backwards Hangman (created by Alex, see here for the first). fill in an "f" - The devil may carry. fill in a "d" - Probably has glasses. fill in a "c" - Popped at the party. fill in ...
5
votes
2answers
626 views

Find multiple dishonest people

Recently I travelled far distance by train and a stranger told me this riddle but I never got the answer: 100 years ago, when far distance travelling was something special, a traveller came back from ...
0
votes
5answers
262 views

What is the largest possible positive number on an 8-segment array? (repeated symbols allowed) [closed]

This is a follow-up to the question, What is the smallest possible positive number on an 8-segment array? However, this time repeats are allowed! You are provided with the 8-segment array in the ...
9
votes
2answers
231 views

Yet another curious incident in the flea circus

The ringmaster of a flea circus puts four fleas $A$, $B$, $C$, $D$ on four different points in the plane that form the corners of a square. Whenever the ringmaster shouts "Hop!", one of the four ...
4
votes
1answer
147 views

Contrasting Partners

She is sunny, while his light does lack. She has a flavour, while he holds something back. Although he is far more solemn, her vividness may make you cringe. Still he goes fittingly with many ...
5
votes
7answers
1k views

What is the smallest positive number on an 8-segment array? (no repeats) [closed]

You are provided with the 8-segment array in the picture together with all the necessary electronics to make any combination of lit segments you want. Fillable version for graphics. http://i.stack....
13
votes
1answer
405 views

Spooky Five Words (-----|||||)

Bringing this puzzle type back again. (See the original for the solution format.) My first is what you will seek. My second is what you should be. My third is something all monsters have. My fourth ...
13
votes
4answers
2k views

The Erasmus pentagon

Professor Erasmus has constructed a special convex pentagon $ABCDE$ that he modestly calls the "Professor-Erasmus-pentagon". The professor claims that he can cut off a smaller pentagon similar to ...
1
vote
2answers
754 views

Forty-Eight: What is the next bigger number?

How to solve this puzzle? Please explain with steps please!
4
votes
3answers
277 views

The Witch Invites

Halloween is just around the corner and the witch is planning a little party for the 100 villagers of the nearby village. Since the villagers burned down her house again and again during the last few ...
16
votes
1answer
264 views

Pumpkin Carving

It's almost Halloween at Farthingbottom School and Professor Charles Flavanna is getting festive. "Right children, put down your copies of The Origins of Fort Monmouth - it's time to carve some ...
-3
votes
1answer
552 views

Maximum tile possible in a game if 2048 on an nXn grid

Playing on an $ n \times n $ grid, how can we determine the largest possible title you can achieve in a game, assuming the computer places tiles in the perfect spots.
-4
votes
7answers
392 views

Crossing the Bridge together [closed]

Two friends each weighing 150 lbs arrive at a Rope bridge 100 yards long. The warning sign at the start of the bridge informs it can hold only a maximum of 325 lbs of weight at any given second, ...
0
votes
2answers
730 views

Walking and cycling [closed]

Claire walks to work at 6km/hr and Charles cycles along the same route. Normally Charles overtakes Claire outside the public library. One day Claire leaves 20 minutes late and Charles overtakes her ...
16
votes
5answers
2k views

Hikers Meeting in the Middle

Two hikers are separated by a two-dimensional mountain range, like the one shown below. The mountain range alternates between peaks and valleys, connected by straight lines. Both hikers are at sea ...
2
votes
2answers
310 views

What's the minimal time needed to get the highest possible sum of tiles in 2048?

I was reading this question / answers realized that people spend a lot more time playing this game than I thought. I find it interesting - although you may not - to know what is the minimal time ...
2
votes
1answer
195 views

Squares in a dot matrix

We have a matrix made up of $m$ by $n$ dots. Can you give a function that counts the number of squares that can be found by joining any $4$ dots in it?
3
votes
1answer
782 views

Crack the code: JavaRelated

I got a card with a text from a software company, and it tells me to decode it. The only thing written on the card is the following code: ...
5
votes
3answers
902 views

A balance and twenty weights

Fredo owns a nice balance with two pans. He now wants to design a system of 20 integer weights $w_1,w_2,\ldots,w_{20}$ with the following properties: $1\le w_1\le w_2\le w_3\le\cdots\le w_{20}$ Any ...
19
votes
1answer
4k views

If you don't care for me, I will hurt you. Who am I?

I come after you are born I'm painful when born I reveal myself when happiness comes But if you do not care for me I will hurt you. Born two times I live no longer as you live. I have two ...
13
votes
2answers
300 views

Monstrous Morphemes

Below are thirteen clues that describe paired words. The first word in each pair is an atrocious attribute. The second word is a fearful figure. The words in the pair share a sort-of stem (or simply a ...
0
votes
0answers
420 views

How do I solve cryptarithmetic puzzles? [duplicate]

An assignment given to us as part of our college course in AI requires us to solve a cryptarithmetic puzzle. The problem is I can't find my way around puzzles - and it was never a problem until now, ...
9
votes
2answers
695 views

Tiling by trapezoids

An equilateral triangle with sidelength $L$ can be tiled by trapezoids with sidelengths $2,1,1,1$. What are the possible values for $L$?
6
votes
2answers
6k views

5 Letter Word, Removing letters - Part 2

Following Part 1: Take away my second letter, and I still sound the same. Take away my third letter, I still sound the same. Even take away my fourth and fifth letters, I will still sound the same. ...
-1
votes
2answers
310 views

Removing black and white balls from a bag in $N$ steps

You have a bag that contains $b$ black balls and $w$ white balls. ($b+w>2$) You put your hand into the bag and pull out a pair of balls. If both balls are black, you throw away one and ...
0
votes
1answer
226 views

The infinite flea circus

Based on Another curious incident in the flea circus and A curious incident in the flea circus by @Gamow There is a $n$ dimensional cube in an $n$ dimensional world. There is a flea on each vertex of ...
13
votes
1answer
1k views

The 100 dollar bill puzzle

Hi, my friend gave me a puzzle, and I need help in solving it. I am required to decrypt this code and get a password. Please help! The hint is: $100 bill. Here's the text version of the image above:...
1
vote
2answers
385 views

How can our secret agent produce a cryptographically secure random number?

Secret Agent Michael Scarn enters his hotel room, only to find it having been ransacked. He needs to send an encrypted message to his handler notifying them that his cover has been compromised. In ...
11
votes
2answers
958 views

Self referential puzzles - follow-up

https://puzzling.stackexchange.com/questions/23554/self-referential-puzzles made me wonder. How many solutions are there to the below box when multiple digits are allowed? I don't know the answer ...
3
votes
1answer
286 views

Yes, I *can* be more metaphorical

Same deal as previous post. One real world source; answers must explain each line and what they all mean when put together. Additionally amongst the mortality, while the final several cadavers ...
11
votes
4answers
2k views

Another curious incident in the flea circus

The ringmaster of a flea circus puts four fleas $A$, $B$, $C$, $D$ on four different points in the plane that form the corners of a square. Whenever the ringmaster shouts "Hop!", one of the four ...
4
votes
1answer
470 views

Could you *be* any more metaphorical?

The following, apparently random list of seemingly random nonsense is a metaphorical interpretation of something that exists in the real world. What is it? As always, go line by line. But once you ...
3
votes
4answers
210 views

A curious incident in the flea circus

The ringmaster of a flea circus puts three fleas $A$, $B$, $C$ on three different numbers on the real number line, so that flea $B$ sits exactly in the middle between $A$ and $C$. Whenever the ...
-6
votes
1answer
117 views

The number of images of the point is.? [closed]

Two plane mirrors facing each other are arranged at $60^o$ to each other. A point is located on the angle bisector. How many images of the point are there?

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